Analysis of differentially expressed genes in LNCaP prostate cancer progression model.

The LNCaP/C4-2 human prostate cancer progression model was established to mimic phenotypic and genotypic changes during prostate cancer development from androgen dependence to androgen independence, from nonmetastasis to metastasis. In this study, cDNA microarrays were performed using a microarray chip from Affymetrix to characterize and compare gene expression profiles in LNCaP and C4-2, which may provide novel insight into the molecular mechanism mediating prostate cancer progression. Three hundred eighteen genes consistently exhibited differential expression in LNCaP and C4-2 in 2-time microarray data. Based on their function, the differentially expressed genes can be grouped into several subcategories, including growth factors and signal transducers, oncogenes and tumor suppressors, tumor-specific antigens, transcriptional factors, transporters, and factors involved in invasion, metastasis, and metabolism. Some genes are novel and unexplored in prostate cancer progression and are of potential interest for follow-up investigation. Reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR were performed to corroborate the microarray results, and 76 differentially expressed genes were validated out of 104 candidates. Expression pattern analyses were performed in these 76 differentially expressed genes, and a series of genes was found to be positively or negatively correlated to prostate cancer progression in the LNCaP prostate cancer progression model and to possess predominant prostate cell specificity. ELF5/ESE-2b and long-chain acyl coenzyme A dehydrogenase (ACADL) expressions were found to be positively associated with malignant progression in LNCaP, C4-2, and C4-2B, and predominantly expressed in prostate cancer cells. Functional evaluation revealed that ELF5/ESE-2b and ACADL expressions contributed to the malignant phenotypes of prostate cancer cells. Accordingly, our microarray data may provide clues for finding novel genes involved in prostate cancer progression to androgen independent and metastasis, and shed light on finding new targets for diagnosis and therapy of prostate cancer.

The radiation response of androgen-refractory prostate cancer cell line C4-2 derived from androgen-sensitive cell line LNCaP.

Radiation therapy is a relatively effective therapeutic method for localized prostate cancer (PCa) patients. However, radioresistance occurs in nearly 30% of patients treated with potentially curative doses. Therapeutic synergy between radiotherapy and androgen ablation treatment provides a promising strategy for improving the clinical outcome. Accordingly, the androgen deprivation-induced signaling pathway may also mediate radiosensitivity in PCa cells. The C4-2 cell line was derived from the androgen-sensitive LNCaP parent line under androgen-depleted condition and had acquired androgen-refractory characteristics. In our study, the response to radiation was evaluated in both LNCaP and C4-2. Results showed that C4-2 cells were more likely to survive from irradiation and appeared more aggressive in their resistance to radiation treatment compared with LNCaP, as measured by clonogenic assays and cell viability and cell cycle analyses. Gene expression analyses revealed that a set of genes involved in cell cycle arrest and DNA repair were differentially regulated in LNCaP and C4-2 in response to radiation, which was also consistent with the radiation-resistant property observed in C4-2 cells. These results strongly suggested that the radiation-resistant property may develop with progression of PCa to androgen-independent status. Not only can the LNCaP and C4-2 PCa progression model be applied for investigating androgen-refractory progression, but it can also be used to explore the development of radiation resistance in PCa.

Ubiquitous mitochondrial creatine kinase is overexpressed in the conditioned medium and the extract of LNCaP lineaged androgen independent cell lines and facilitates prostate cancer progression.

BACKGROUND: Androgen independent prostate cancer (AIPC) is not responsive to androgen ablation therapy. The biomarkers of AIPC are lack. Numerous proteomics studies have focused on finding new markers of AIPC and exploring their possible functions, but little is known about the difference between conditioned medium (CM) from AIPC and androgen dependent prostate cancer (ADPC) cells. METHODS: We performed a proteome analysis of CM from LNCaP, C4-2, and C4-2B cells by a two dimensional electrophoresis based technology. Western blots and immunohistochemical studies were employed to explore the expression pattern of the identified protein in prostate cancer cell lines and clinical specimens, respectively. Then we examined the possible roles and mechanisms of the ubiquitous mitochondrial creatine kinase (uMtCK) in vitro. RESULTS: Besides prostate specific antigen (PSA) and insulin-like growth factor binding protein-2 (IGFBP2), uMtCK was identified in the CM of AIPC cells. uMtCK was up-regulated in AIPC cells and in human prostate cancer tissues at WHO grade III. Stably transfected exogenous uMtCK showed a growth promoting effect rather than mock vector in LNCaP cells, with or without bicalutamide in culture medium. Further assays showed that higher degrees of ROS generation and Akt signaling pathway activation in LNCaP-uMtCK than in LNCaP-neo cells. CONCLUSIONS: We showed that uMtCK could be easily detected in CM of LNCaP lineaged AIPC cells. Exogenous uMtCK in LNCaP cells surprisingly contributed to overproduction of ROS, activation of Akt signaling pathway and more aggressive phenotypes including androgen independence development.